**BLINKBLINK** And that’s what I get for writing a response before reading all the comments– didn’t realize (but should have) that Ed had written a filk below. His is MUCH better than my sorry attempt!

Exercise to the reader – if, for purely practical purposes, we constrain St. Charlie’s speed to that of the fastest currently known train (Japan’s MXL, 581 km/h), and “never” to span from today (August 6, noon 12:00 GMT sharp) to the expected end-of-life of Earth (500 million to 900 million years in the future, give or take), how much (contiguous!) track would one need “never to return”…?

…Then again things (and the passengers) being what they are, it’s of course entirely possible that she’s traversing between multiple extra dimensions / realities, which would make that a lot easier…

It’s a simple question to answer.
In standard Einsteinian 4-dimensional spacetime, masses being unable to be accelerated to the speed of light, and t always increasing, it is impossible to return to the same point in spacetime; not just where, but when.
However, wormholes, FTL travel, infinitely long rotating cylinders, and other non-standard spacetime connectivity might allow timelike loops, i.e. returning to the same point in spacetime.

If the world ends in exactly 500 million years, and if the city is always traveling at that top speed, 2.546 quadrillion kilometers.

Then again, that doesn’t tell you much. If we calculate the density of track over the Earth’s surface, we get… huh. Very close to 5000 linear meters per square meter.

But St. Charlie is parked right now, so that throws off those calculations. Assuming instead a leisurely average speed of 5 kph, the city requires 43.03 linear meters of track per square meter of Earth’s surface. Depending how wide and how tall the train is, the tracks might have to be tiered up to several kilometers.

Or the city and/or world could be destroyed first.

Or the world could change so much between visits of the same geographical location that it can’t really count as “returning.”

Ah, but what flavor of Wifi: 802.11a, -b, -g, -n, or -ac? And what’s the St. Charlie using for the backhaul to the Internet backbone? It’d be a pity if it has 802.11ac for the wireless LAN with an old V.34 acoustic modem for the WAN.

802.11q was erased from public consumption because the first silicon had a nasty tendency to consume the public. Those fools at the IEEE were told time and again to use gallium nitride as a substrate, but noooOOOooo, “silicon would enable faster die spins during development”. Never mind the fact that the silicon was a perfect growth medium for the n-th dimensional noosvores drawn by the summoning circuit created by the first draft 802.11q physical layer…

No, but you should be more specific. “The sports channel on the satellite T.V. It’s not just curling, is it? And the porn channels? Does that include goblin? Does that include *only* goblin? And wifi, who pays for that?”